Sometimes more information is needed about the internal condition of trees and Treecall Consulting has a range of equipment that can be used to carry out in-depth investigations to determine appropriate tree management.
PiCUS Sonic Tomograph
The PiCUS Sonic Tomograph is an instrument for the detection of decay and cavities in standing trees.
Nails are driven through the bark around the circumference of the tree, to which sensors are attached. Each nail is struck in turn with a hammer and the sensors detect the resulting sound waves as they travel across the tree. The data received by the sensors is transmitted to a laptop and the software compares the speed of the sound waves. If the speed of travel is reduced in a particular area, this indicates that there may some decay, a cavity or an internal crack.
The results are shown as a cross section of the trunk showing the variations in speed of the sound waves in different colours. A brown or buff colour indicates good quality wood with insignificant strength loss. Purple, blue and white indicate progressively greater decay or dysfunction, white being the most significant and normally indicating hollows. The green colours indicate wood of intermediate characteristics, where there is likely to be some decay in its early stages.
The Resi-PD 500 is a microdrill that records the resistance of wood to the passage of its drill bit through a trunk or branch. Readings are taken just at the chosen points where information is needed about wood strength.
Regions of sound wood show high resistance to the forward motion of the drill bit, but as it enters a decayed region this resistance is reduced. The level of resistance along the path of the drill is displayed as a continuous trace and this enables the wood quality in different areas of the tree to be compared.
When light energy is absorbed by the chlorophyll in a leaf there are three processes at work: some of the energy is used to drive photosynthesis (photochemistry) and the excess can either be dissipated as heat or re‐emitted as light (chlorophyll fluorescence).
Current research suggests that chlorophyll fluorescence can be used to measure plant vitality and future growth potential. Values in the range 0.85-0.75 indicate a healthy plant and ‘normal’ growth, representative of the species, whereas lower values correlate with increasing levels of stress in the plant. In trees, a drop in values below 0.25 is often accompanied by signs of leaf drop and cessation of growth.
Treecall Consulting takes chlorophyll fluorescence readings using a small hand-held device called the ‘Pocket Pea’, produced by Hansatech. This instrument works by illuminating a dark-adapted leaf with a very bright red LED for around 1 second and recording the chlorophyll fluorescence signal that is emitted. The values obtained can help us to assess the overall health of the tree and where some intervention, such as soil decompaction or fertilisation, may be beneficial to improve vitality.
The air spade is a tool that enables the soil surrounding trees to be removed without damaging roots.
Compressed air is directed onto the soil which is blown away from the root surface. This method avoids inadvertent damage from spades or other hand tools and allows the tree root structure or decayed areas to be inspected or for underground services or foundations to be installed without the need for severing roots.
This method is also used where poor quality or contaminated soil is to be replaced with better quality material to encourage healthy tree growth.